/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_PGTABLE_3LEVEL_H
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#define _ASM_X86_PGTABLE_3LEVEL_H
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#include <asm/atomic64_32.h>
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/*
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* Intel Physical Address Extension (PAE) Mode - three-level page
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* tables on PPro+ CPUs.
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*
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* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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*/
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#define pte_ERROR(e) \
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pr_err("%s:%d: bad pte %p(%08lx%08lx)\n", \
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__FILE__, __LINE__, &(e), (e).pte_high, (e).pte_low)
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#define pmd_ERROR(e) \
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pr_err("%s:%d: bad pmd %p(%016Lx)\n", \
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__FILE__, __LINE__, &(e), pmd_val(e))
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#define pgd_ERROR(e) \
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pr_err("%s:%d: bad pgd %p(%016Lx)\n", \
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__FILE__, __LINE__, &(e), pgd_val(e))
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/* Rules for using set_pte: the pte being assigned *must* be
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* either not present or in a state where the hardware will
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* not attempt to update the pte. In places where this is
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* not possible, use pte_get_and_clear to obtain the old pte
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* value and then use set_pte to update it. -ben
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*/
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static inline void native_set_pte(pte_t *ptep, pte_t pte)
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{
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ptep->pte_high = pte.pte_high;
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smp_wmb();
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ptep->pte_low = pte.pte_low;
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}
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#define pmd_read_atomic pmd_read_atomic
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/*
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* pte_offset_map_lock() on 32-bit PAE kernels was reading the pmd_t with
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* a "*pmdp" dereference done by GCC. Problem is, in certain places
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* where pte_offset_map_lock() is called, concurrent page faults are
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* allowed, if the mmap_lock is hold for reading. An example is mincore
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* vs page faults vs MADV_DONTNEED. On the page fault side
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* pmd_populate() rightfully does a set_64bit(), but if we're reading the
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* pmd_t with a "*pmdp" on the mincore side, a SMP race can happen
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* because GCC will not read the 64-bit value of the pmd atomically.
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*
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* To fix this all places running pte_offset_map_lock() while holding the
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* mmap_lock in read mode, shall read the pmdp pointer using this
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* function to know if the pmd is null or not, and in turn to know if
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* they can run pte_offset_map_lock() or pmd_trans_huge() or other pmd
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* operations.
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*
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* Without THP if the mmap_lock is held for reading, the pmd can only
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* transition from null to not null while pmd_read_atomic() runs. So
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* we can always return atomic pmd values with this function.
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*
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* With THP if the mmap_lock is held for reading, the pmd can become
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* trans_huge or none or point to a pte (and in turn become "stable")
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* at any time under pmd_read_atomic(). We could read it truly
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* atomically here with an atomic64_read() for the THP enabled case (and
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* it would be a whole lot simpler), but to avoid using cmpxchg8b we
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* only return an atomic pmdval if the low part of the pmdval is later
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* found to be stable (i.e. pointing to a pte). We are also returning a
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* 'none' (zero) pmdval if the low part of the pmd is zero.
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*
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* In some cases the high and low part of the pmdval returned may not be
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* consistent if THP is enabled (the low part may point to previously
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* mapped hugepage, while the high part may point to a more recently
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* mapped hugepage), but pmd_none_or_trans_huge_or_clear_bad() only
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* needs the low part of the pmd to be read atomically to decide if the
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* pmd is unstable or not, with the only exception when the low part
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* of the pmd is zero, in which case we return a 'none' pmd.
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*/
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static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
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{
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pmdval_t ret;
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u32 *tmp = (u32 *)pmdp;
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ret = (pmdval_t) (*tmp);
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if (ret) {
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/*
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* If the low part is null, we must not read the high part
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* or we can end up with a partial pmd.
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*/
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smp_rmb();
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ret |= ((pmdval_t)*(tmp + 1)) << 32;
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}
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return (pmd_t) { ret };
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}
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static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
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{
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set_64bit((unsigned long long *)(ptep), native_pte_val(pte));
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}
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static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
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{
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set_64bit((unsigned long long *)(pmdp), native_pmd_val(pmd));
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}
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static inline void native_set_pud(pud_t *pudp, pud_t pud)
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{
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#ifdef CONFIG_PAGE_TABLE_ISOLATION
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pud.p4d.pgd = pti_set_user_pgtbl(&pudp->p4d.pgd, pud.p4d.pgd);
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#endif
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set_64bit((unsigned long long *)(pudp), native_pud_val(pud));
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}
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/*
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* For PTEs and PDEs, we must clear the P-bit first when clearing a page table
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* entry, so clear the bottom half first and enforce ordering with a compiler
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* barrier.
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*/
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static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep)
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{
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ptep->pte_low = 0;
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smp_wmb();
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ptep->pte_high = 0;
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}
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static inline void native_pmd_clear(pmd_t *pmd)
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{
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u32 *tmp = (u32 *)pmd;
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*tmp = 0;
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smp_wmb();
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*(tmp + 1) = 0;
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}
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static inline void native_pud_clear(pud_t *pudp)
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{
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}
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static inline void pud_clear(pud_t *pudp)
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{
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set_pud(pudp, __pud(0));
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/*
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* According to Intel App note "TLBs, Paging-Structure Caches,
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* and Their Invalidation", April 2007, document 317080-001,
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* section 8.1: in PAE mode we explicitly have to flush the
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* TLB via cr3 if the top-level pgd is changed...
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*
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* Currently all places where pud_clear() is called either have
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* flush_tlb_mm() followed or don't need TLB flush (x86_64 code or
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* pud_clear_bad()), so we don't need TLB flush here.
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*/
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}
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#ifdef CONFIG_SMP
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static inline pte_t native_ptep_get_and_clear(pte_t *ptep)
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{
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pte_t res;
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res.pte = (pteval_t)arch_atomic64_xchg((atomic64_t *)ptep, 0);
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return res;
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}
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#else
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#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
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#endif
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union split_pmd {
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struct {
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u32 pmd_low;
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u32 pmd_high;
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};
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pmd_t pmd;
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};
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#ifdef CONFIG_SMP
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static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp)
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{
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union split_pmd res, *orig = (union split_pmd *)pmdp;
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/* xchg acts as a barrier before setting of the high bits */
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res.pmd_low = xchg(&orig->pmd_low, 0);
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res.pmd_high = orig->pmd_high;
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orig->pmd_high = 0;
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return res.pmd;
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}
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#else
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#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
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#endif
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#ifndef pmdp_establish
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#define pmdp_establish pmdp_establish
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static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmdp, pmd_t pmd)
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{
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pmd_t old;
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/*
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* If pmd has present bit cleared we can get away without expensive
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* cmpxchg64: we can update pmdp half-by-half without racing with
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* anybody.
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*/
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if (!(pmd_val(pmd) & _PAGE_PRESENT)) {
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union split_pmd old, new, *ptr;
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ptr = (union split_pmd *)pmdp;
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new.pmd = pmd;
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/* xchg acts as a barrier before setting of the high bits */
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old.pmd_low = xchg(&ptr->pmd_low, new.pmd_low);
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old.pmd_high = ptr->pmd_high;
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ptr->pmd_high = new.pmd_high;
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return old.pmd;
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}
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do {
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old = *pmdp;
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} while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd);
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return old;
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}
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#endif
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#ifdef CONFIG_SMP
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union split_pud {
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struct {
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u32 pud_low;
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u32 pud_high;
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};
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pud_t pud;
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};
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static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
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{
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union split_pud res, *orig = (union split_pud *)pudp;
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#ifdef CONFIG_PAGE_TABLE_ISOLATION
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pti_set_user_pgtbl(&pudp->p4d.pgd, __pgd(0));
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#endif
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/* xchg acts as a barrier before setting of the high bits */
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res.pud_low = xchg(&orig->pud_low, 0);
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res.pud_high = orig->pud_high;
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orig->pud_high = 0;
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return res.pud;
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}
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#else
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#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp)
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#endif
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/* Encode and de-code a swap entry */
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#define SWP_TYPE_BITS 5
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#define SWP_OFFSET_FIRST_BIT (_PAGE_BIT_PROTNONE + 1)
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/* We always extract/encode the offset by shifting it all the way up, and then down again */
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#define SWP_OFFSET_SHIFT (SWP_OFFSET_FIRST_BIT + SWP_TYPE_BITS)
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#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > 5)
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#define __swp_type(x) (((x).val) & 0x1f)
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#define __swp_offset(x) ((x).val >> 5)
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#define __swp_entry(type, offset) ((swp_entry_t){(type) | (offset) << 5})
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/*
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* Normally, __swp_entry() converts from arch-independent swp_entry_t to
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* arch-dependent swp_entry_t, and __swp_entry_to_pte() just stores the result
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* to pte. But here we have 32bit swp_entry_t and 64bit pte, and need to use the
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* whole 64 bits. Thus, we shift the "real" arch-dependent conversion to
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* __swp_entry_to_pte() through the following helper macro based on 64bit
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* __swp_entry().
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*/
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#define __swp_pteval_entry(type, offset) ((pteval_t) { \
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(~(pteval_t)(offset) << SWP_OFFSET_SHIFT >> SWP_TYPE_BITS) \
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| ((pteval_t)(type) << (64 - SWP_TYPE_BITS)) })
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#define __swp_entry_to_pte(x) ((pte_t){ .pte = \
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__swp_pteval_entry(__swp_type(x), __swp_offset(x)) })
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/*
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* Analogically, __pte_to_swp_entry() doesn't just extract the arch-dependent
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* swp_entry_t, but also has to convert it from 64bit to the 32bit
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* intermediate representation, using the following macros based on 64bit
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* __swp_type() and __swp_offset().
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*/
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#define __pteval_swp_type(x) ((unsigned long)((x).pte >> (64 - SWP_TYPE_BITS)))
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#define __pteval_swp_offset(x) ((unsigned long)(~((x).pte) << SWP_TYPE_BITS >> SWP_OFFSET_SHIFT))
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#define __pte_to_swp_entry(pte) (__swp_entry(__pteval_swp_type(pte), \
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__pteval_swp_offset(pte)))
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#include <asm/pgtable-invert.h>
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#endif /* _ASM_X86_PGTABLE_3LEVEL_H */
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